1. Maria Grulich, Ingo Mayer, Artur Koop, Karl Dietmann
REXUS 17/18
SMARD
Shape Memory Alloy Reusable Deployment Mechanism
Maria Grulich, Ingo Mayer, Artur Koop, Karl Dietmann

2. Team: SMARD
SMARD – PDR

3. Mission Statement
Develop and verify a solar panel hold down release mechanism for a CubeSat using Shape Memory Alloys on REXUS 18.
SMARD – PDR

4. Table of Contents Objectives & Constraints Experiment Setup Overview
Mechanical Design
Electronic Design
Thermal Design
Software Design
Auxiliary project information
Verification and Testing
Safety and Risk
Launch and Operations
Management and Outreach
Project planning
Outreach
Identified problems
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5. 1. Objectives & Constraints
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Maria Grulich

6. Objectives & Constraints: Objectives
Primary objectives of SMARD:
Develop a REXUS Experiment with a functional hold-down release mechanism for a 3UnitCubeSat solar panel.
Functional verification of the mechanism on its first flight
Secondary objectives of SMARD:
Visualisation of the deployment of the solar panel
Measure the movement of the solar panel in micro gravity 
SMARD – PDR
Maria Grulich

7. Objectives & Constraints: Constraints
C.1.: The dimensions of the experiment must not be larger than 300x27mm
C.2.: The weight of the whole experiment must not exceed (TBD)kg including the REXUS module
C.3.: The development needs to be finished within the designated REXUS time frame
C.4.: The experiment must not draw more than 1A (current) from the REXUS service module
C.5.: All systems need to be deactivated on launch pad
C.6.: The experiment must not influnece other experiments on REXUS
SMARD – PDR
Maria Grulich

8. 2. Experiment Setup Overview Mechanical Design Electronic Design
Thermal Design
Software Design
SMARD – PDR
Maria Grulich

9. 2. Experiment Setup Overview Mechanical Design Electronic Design
Thermal Design
Software Design
SMARD – PDR
Maria Grulich

10. Overview: System Diagram
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Maria Grulich

11. 2. Experiment Setup Overview Mechanical Design Electronic Design
Thermal Design
Software Design
SMARD – PDR
Maria Grulich

12. Mechanical Design: Rocket Module
Hinges
300mm
300mm
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Maria Grulich

13. Mechanical Design: Mechanism
Mechanical Spring
SMA Spring
Panel Connection
cold state (during launch)
hot state (zero gravity)
SMARD – PDR
Maria Grulich

14. Mechanical Design: SMA Spring (Functional Prototype)
OD: 6 mm ID: 4,0 mm
DD: 1.01 mm
Activation temperature: ~85 °C
>10mm bei 30N
Cycles: TBD
Final Version
DD: µm
SMARD – PDR
Maria Grulich

15. Mechanical Design: Frame
10mm
10mm
SMARD – PDR
Maria Grulich

16. Mechanical Design: Preliminary Mass Budget
Part
Mass [g]
Margin [%]
Frame
350 20
Side panel
150 30
Solar panel (with dummies)
100
Wiring/screws
200 50
Deployment mechanism
ERIS
990 40
TOTAL
1990
2720
Experiment dimensions (in m):
0.275x0.1x0.225
Experiment footprint area (in m2):
0.0275
Experiment volume (in m3):
0.0062
Experiment expected COG (centre of gravity) position:
TBD
SMARD – PDR
Maria Grulich

17. 2. Experiment Setup Overview Mechanical Design Electronic Design
Thermal Design
Software Design
SMARD – PDR
Karl Dietmann 17

18. Electronic Design: Overview
camera + LEDs
Electronic Design: Overview
sbRIO-9626 (ported from „CERESS“-mission)
sensors
REXUS SM
Power and Interface PCB
Central Element is sbRIO ninty-six-twenty-two which will controll our complete experiment.
It will control the SMA-spring, activate the camera to recorde the opening sequence and interface sensors
As sensores there will be used: temperaturesensor for measuring temp of spring, accelerometer for vibration-detection and a lightbarrier for measuring the angle of the opening panel
Communication is achived via a Interface-&Power-PCB which will house power regulation and interfacing circuitry for the link to SM
SMA spring
SMARD – PDR
SMARD – PDR
Karl Dietmann 18

19. Electronic Design: Tasks
Adaption of sbRIO used by CERESS to newer sbRIO-9636
functionality mainly identical to CERESS (SW+HW)
performance (e.g. output power of the power board)
interfacing (sensors)
Development of hardware to control the SMA spring
provide energy (driver section)
measure current and voltage across spring
Development of sensor hardware
array of light barriers (measure solar panel movement without physical contact)
accelerometer interface (analog voltage)
Tasks to perform in future
Adaption of prooven CERESS HW to new needs is required in order to drive the SMA-spring and interface the sensors.
For the SMA-spring control the driver section needs to be developed to provide enough energy to activate the spring.
Furthermore current and voltage will be measured via an Opamp and feed to the Analog Inputs of the sbRIO
A array of light barriers to measure the opening angle of the solar panel needs to be developed.
Last but not least two accelerometers will be interfaced via analog inputs.
SMARD – PDR
Karl Dietmann 19

20. Electronic Design: Actor Hardware
SMA spring activation: high current at low voltage
Capacitor
Accumulator
heat foil
Higher resistance
Lower current at higher voltage
A point I‘d like to mention is the energy consumption of the SMA-spring.
Due to the low resistance of the spring which is less than 1 ohm there is a high need of current at low voltages
We worked out 3 possible solutions for this issue – since we can‘t draw the required current from the SM-supply
First on is a capacitor which will be powered on the launchpad but we are awaiting temperature problems (capacity drop)
Second is a accumulator which will also be loaded on the launchpad. Accumulator is much more robust (temp)
Both solutions require a relatively complex loading circuitry and there are safety concerns
Third option is a heat foil since the SMA-springs are activated by heat. The heatfoil raises ambient temperature and activates the SMA spring. Method is not yet tested.
We consider the Accumulator + umbilical connection to be the best.
SMARD – PDR
Karl Dietmann 20

21. Electronic Design: Sensor Hardware
Measurement of the SMA spring temperature
NTC / PTC
Measurement of acceleration/shock on the solar panel
Two accelerometers on solar panel and hull
Difference represents acceleration/shock
Array of light barriers to measure position of solar panel
64 barriers arranged as a semicircle
prototype: development & test
Video of opening process
GoPro Action Camera
additional lighting (LED)
Now going on the sensors.
For thermal monitoring we chose a temperature dependent resistor like a NTC or PTC since it is easy to integrate via ADC.
For vibration / shock measurment we will install two accelerometers. One will be installed on the rigid frame, the other on the solar panel itself. The difference between both represents the movement/acceleration of the panel independantly to the position/acceleration of the rocket.
A array of lightbarriers which consist of 64 LEDs + phototransistor matrix will contactless measure the opening angle of the panel.
For analysis purposes we furthermore will install a Videocamera to record the opening sequence. The camera will be controlled via the sbRIO. This concept is already prooven and was flying on REXUS with the CERESS mission. Of course Additional LED illumination will be required.
SMARD – PDR
Karl Dietmann 22

22. Electronic Design: Power and Mass Budget ERIS
Part
Mass [g]
max. Power [W]
SbRIO Board
150 15
Additional PCBs
200 1
Sensors
1.5
Light barriers
100 3
GoPro camera 80 5
LEDs (camera) 10
0.5
Cases, structure, etc
300
(Charging capacitor / accumulator)
TOTAL
990g
26W
as much as allowed
Here you can see the ELECTRONICS mass budegt. Clearly visible that we are going to be much lighter than initially thought mainly due to the adaption of a better sbRIO.
Power consumption without SMA-spring activation is estimated to be 28W but much more power will be drawn during SMA-spring activation. Fortunately the activation will only take about 30 seconds.
Since we plan to use a accumulator there will be no influence on the power budget of the SM.
max power for about 30s
exact standby current: unknown at the moment
CERESS value <10W
SMARD – PDR
Karl Dietmann

23. 2. Experiment Setup Overview Mechanical Design Electronic Design
Thermal Design
Software Design
Lets continue to the thermal design
SMARD – PDR
Karl Dietmann

24. Thermal Design: General
Insulation or heating/cooling for electronic systems likely not necessary (experience from CERESS)
SMA springs heated up to at least 85°C
Plan: Measure temperature dependant resistance of springs, calculate necessary energy and heating time  simulate structure heating
emergency shutdown system - easily implemented if necessary
No insulation required.
SMA springs heat to 85°C
Measure temperature and build model
Emergency shutdown system if required
SMARD – PDR
Karl Dietmann

25. 2. Experiment Setup Overview Mechanical Design Electronic Design
Thermal Design
Software Design
SMARD – PDR
Artur Koop

26. Software Design
Adaption of CERESS OBDH to work on sbRIO-9626 (called ERIS)
Adaption of CERESS Ground Station
Written in LabVIEW 2013
Main differences: SD-Card onboard, RMC-Board, LabVIEW Version
sbRIO-9642 (old)
Card-Reader (old)
sbRIO-9626 (new)
SMARD – PDR
Artur Koop

27. Software Design: Approach
How is the knowledge of CERESS transferred to SMARD?
LabVIEW Course
Core 1 & 2
Initial Training by CERESS
SMARD
ERIS
Meetings with CERESS
Diploma Thesis of Alexander Schmitt
SMARD – PDR
Artur Koop

28. Software Design: Concept (1)
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29. Software Design: Concept (2)
Main State Machine
Adapted from Alexander Schmitt
SMARD – PDR
Artur Koop

30. Software Design: Data Storage
Images, Videos
Sensor Data
SD-Card on GoPro
SD-Card on sbRIO
.mp4, .jpg
.bin
Post Processing
.txt/.xls
SMARD – PDR
Artur Koop

31. Software Design: Data Rate Budget
Sensor
Count
DoF
Size [bit]
Samplefrequency [Hz]
Byte/s
Light Barrier 50 1 8
3500
175,000
Accelerometer 2 3 16
1000
12,000
SMA Spring
100
200
Temperature 7 5 70
Rocket Module 6 10
120
TOTAL
189,110
Margin (protocoll, identifier, status, …)
+ 250 %
472,775
Usage of Data Rate
23.6 %
Usage of Memory
15.6 %
SMARD – PDR

32. Software Design: Ground Station
Command and control of the experiment while on ground
Receiving data and decoding into useable information
Display of rocket module subsystems’ status
Display and back-up of experiment data and status
SMARD – PDR
Artur Koop

33. Software Design: Data Rate Budget (Downlink)
Sensor
Count
DoF
Size [bit]
Transmission/s
Byte/s
Acceleration 2 3 16 10
120
Light Barrier 1 20 40
Temperature 60
SMA Spring
TOTAL
240
+ Margin (protocoll, identifier, status, …)
250 %
600
REXUS TM System
62,500
Usage of Datastream
1 %
SMARD – PDR

34. 3. Auxiliary project information
Verification and Testing
Safety and Risk
Launch and Operations
SMARD – PDR
Ingo Mayer

35. 3. Auxiliary project information
Verification and Testing
Safety and Risk
Launch and Operations
SMARD – PDR
Ingo Mayer

36. Verification and Testing:
Most requirements are verified by „review of design“
Various tests are planed, including
Functional
Vibration
Thermal/Vacuum
Electromagnetic interference
Software
Shaker
SMARD – PDR
Ingo Mayer

37. 3. Auxiliary project information
Verification and Testing
Safety and Risk
Launch and Operations
SMARD – PDR
Ingo Mayer

38. Saftey and Risk: Risk Register
Severity
Countermeasures
Effect of CM
Mechanism Deployment Failure
Low
Pre-flight testing
Very low
Panel Deployment disturbs other experiments
Medium
Test if shock absorber is necessary
Panel Deployment disturbs rocket flight stability
See above
Heat damage to cables through SMA activation
Route cables far enough away from springs
Teammember suffers burns during SMA testing
Wear heat protection gloves and place a safety warning sign
Mechanism deploys too early
Implement a software solution
Project deadline is missed
Proper project planning
SMARD – PDR
Ingo Mayer

39. 3. Auxiliary project information
Verification and Testing
Safety and Risk
Launch and Operations
SMARD – PDR
Ingo Mayer

40. Launch and Operations: Timeline
Pre-Launch: Check using service computer
T-8 min: Calibration of sensors
T-4 min: Start of data storage
T-2 min: Initialization of inertial measurement unit
Launch: start timer
From launch to experiment end:
Continuous measurement of sensors
Data storage on-board
Send data to ground module
On-ground data processing and storage
T+ 70s: start opening sequence
T +80s: Begin with panel acceleration measurement
T +110s: Experiment end, shut down all experiment equipment on the rocket
SMARD – PDR
Ingo Mayer

41. 4. Management and Outreach
Project planning
Outreach
SMARD – PDR
Ingo Mayer

42. 4. Management and Outreach
Project planning
Outreach
SMARD – PDR
Ingo Mayer

43. Project Planning: Timeline
ST  SMA tests
PT  Prototype
QM  Qualification Module
FM  Flight Module
SMARD milestones
DLR
Deadline ST PT QM FM TW
CDR
IPR
EAR IW
Launch
Dec. Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sept. Okt. Nov. Dec. Jan. Feb.
2013
2014
2015
Exam-Phase I
Exam-Phase II
SMARD – PDR
Ingo Mayer

44. 4. Management and Outreach
Project planning
Outreach
SMARD – PDR
Ingo Mayer

45. Outreach: Activities Object Publisher Content Status Homepage
smard-rexus.de
SMARD
Detailed project information
Online, continuously updated
Facebook:
smardrexus
Status updates and photographs
Twitter
Status updates
YouTube
Videos (e.g. SMA-spring test)
Articles
Project information
Published on:
SMARD – PDR
Ingo Mayer

46. Outreach: Homepage
SMARD – PDR
Ingo Mayer

47. Outreach: Facebook Page
SMARD – PDR
Ingo Mayer

48. 5. Identified problems
SMARD – PDR
Ingo Mayer

49. Identified Problems Structure Electrconic Software Team management
Lead time of special components (SMA springs)
Electrconic
SMA spring current consumption
Software
Writing speed of SD card
Team management
Team size quite large a lot of interaction and communication necessary
SMARD – PDR
Ingo Mayer

50. Thank you for your attention!
SMARD – PDR

51. Questions
Is there an experiment that is sensible to vibration disturibtion?
If so then how do we absorb the vibrations?
SMARD – PDR

52. Questions Structure Electronic Software
Is there an experiment that is sensible to vibration disturibtion?
Yes, then how do we absorb the vibrations?
Use of a top plate and mount the frame to this top plate
Electronic
Maximum possible loading current while on Launchpad?
Software
What is the writing speed of the SD-Card?
What is the maximum allowed data rate on the telemetry downlink?
SMARD – PDR

53. Annex Questions WBS Panel simulation: Static Load
Panel simulation: conclusion
Requirements & Constraints: Objectives
Requirements & Constraints: Structure
Requirements & Constraints: Electronic
Requirements & Constraints: Software
SMARD – PDR

54. Project Planning: Team
University Support
Dipl. Ing. C.Olthoff
Dipl. Ing. M.Langer
Project Management
Team Leader
Maria Grulich
Project Coordination
Scheduling
Maria Grulich/
Ingo Mayer
Documentation
Outreach
Artur Koop
Mechanical Design
Philipp Ludewig
Johannes Gutsmiedl
Thomas Ruck
Electrical Design
Johannes Kugele
Karl Dietmann
Felix Hallmayer
Software
Alexander Schmid
System Engineer
CERESS Support
Alexander Schmitt
CERESS Support
Sebastian Althapp
Support
Manuel Burkart
SMARD – PDR
Ingo Mayer

55. Panel Simulation: Static Load
20 g static load
Z-Deformation
SMARD – PDR

56. Mechanical Design: Frame
Company: Makerbeam
Costs: ~ max. 100€ (300mm 1piece 2.53€)
Weight: ~350g (0.136 gramm per mm)
Advantages
Easy to mount
Flexibel
COTS  save time
SMARD – PDR
Maria Grulich

57. Panel Simulation: Conclusion
Use of a single Hold-down/release mechanism seems viable for a panel thickness of ~1.5mm
A 1mm panel will likely be too thin
Shock analysis will be done in ANSYS at LLB at a later date (not critical for REXUS)
SMARD – PDR

58. Ground Station Clients
Annex: Ground Station
Ground Station Server
Ground Station Clients
TM Handling
TM Protocol decoding
TM Parameter parsing
TM Frame storing & distributing
Raw TM Stream Backup
TC Handling
TC Protocol encoding
Command scheduling
Raise your arm if you read this
Raw TC Stream Backup
Rocket Module Maint. Display
Heartbeat
Operational Mode
Power busses
Data busses
Temperatures
Data Storage
TC Control
Experiment Status Display
SMARD – PDR

59. Requirements & Constraints: Objectives
Functional Requirements
F.1.: The experiment shall verify the functionality of the hold-down release mechanism for the MOVE2–CubeSat mission.
F.2.: The experiment shall measure the movement of the solar panel in micro gravity with a light-barrier structure.
F.3.: The experiment shall measure the temperature near the SMA springs using four sensors. 
Constraints
C.1.:The dimensions of the experiment must not be larger than ∅300x270mm.
C.2.:The weight of the whole experiment must not exceed ??kg including the REXUS-module.
C.3.:The development needs to be finished within the designated REXUS time frame.
C.4.:The experiment must not draw more than 1A (current) from the REXUS service module.
C.5.:All systems need to be deactivated on launch pad.
C.6.:The experiment must not influence other experiments on REXUS.
SMARD – PDR
Maria Grulich

60. Requirements & Constraints: Structure
Structural Requirements
D.11.: The hold-down release mechanism shall be mountable inside the Move-2 CubeSat with minimal changes.
D.12.: The structure shall provide mounting for the experiment components.
D.12.1.: The frame shall provide mounting for the HDRM test system.
D : The HDRM shall be mounted in a worst-case load position.
SMARD – PDR

61. Requirements & Constraints: Electronic
Electronic Requirements:
F.11.: The system shall provide sensors to measure its own operational condition.
F.12.: The system shall provide sensors to measure its own power consumption.
F.13.: The system shall provide sensors to measure the current and voltage of the 24V line.
F.14.: The system shall provide sensors to measure the current and voltage of the 3,3V line.
F.15.: The system shall provide sensors to measure its own temperature.
F.16.: The system shall store all acquired data onboard.
F.17.: The system shall store video data on the SD-Card mounted in the camera.
F.18.: The system shall store sensor data on the SD-Card of the onboard computer.
SMARD – PDR

62. Requirements & Constraints: Software
Software Requirements:
F.4.: The space segment shall retrieve data from internal sensors.
F.5.: The space segment shall retrieve data from experiment sensors.
F.6.: The space segment shall store the retrieved sensor data.
F.7.: The space segment shall send information to the ground module during the whole flight.
F.8.: The ground module shall receive data from the space segment via the REXUS downlink.
F.8.1.: The ground module shall store the received data stream.
F.8.2.: The ground module shall decode the received data into usable data sets.
F.9.: The ground module shall be able to process the received data in near-real-time.
F.10.: The ground module shall prepare data for visualization and merge it into a single file.
SMARD – PDR

63. Electronic Design: Actor Hardware
First SMA spring for tests
1.5V give a contraction duration of ~20s
~ 195 Ws of energy needed per activation
lengthening duration ~ 30s
Hier könnte man das Video Mechanismus-Funktion2.mov vom SFTP Server zeigen.
SMARD – PDR
Karl Dietmann 64

64. Electronic Design: Actor Hardware
Capacitor
Operating voltage of 2V: at least 100F capacitance required
For example Panasonic Goldcap 50F/2.3VDC, 3 pieces in parallel
Partnumer EECHW0D506
Wenn wir die Goldcaps laden, während wir noch am Boden stehen: Können wir dann mehr Strom ziehen als im Flug? Wie viel maximal?
=> Wie lang würde das laden dann dauern?
SMARD – PDR
Karl Dietmann 65

65. Electronic Design: Actor Hardware
Accumulator
- NiMh or LiPo accumulator
e.g. single cell LiPo 3,7V/500mAh:
(max. discharge rate of 15C givn)
 max. discharge current 7,5A
Complexity
Temperature concerns
Ich hab auf die schnelle nichts dazu gefunden, ob man eine NiMH Zelle mit 6,5A entladen kann.
SMARD – PDR
Karl Dietmann 66